#include "hashmap.h"
#include <stdlib.h>
#include <stdio.h>
#define DEFAULT_CAP 16

void hm_init (
    struct hash_map* map,
    hm_hash_fn hash_fn,
    hm_eq_fn eq_fn,
    hm_destroy_fn destroy_fn
) {
    map->cap = DEFAULT_CAP;
    map->entries = ccc_alloc(map->cap * sizeof(void*));
    map->hash_fn = hash_fn;
    map->eq_fn = eq_fn;
    map->destroy_fn = destroy_fn;
}

void hm_destroy(struct hash_map* map) {
    for (integral_t i = 0; i < map->cap; i++) {
        if (map->entries[i] == NULL) continue;
        if (map->destroy_fn != NULL) map->destroy_fn(map->entries[i]);
        free(map->entries[i]);
    }
    free(map->entries);
}

void** hm_cell_r(const struct hash_map* map, const void* entry) {
    integral_t idx0 = map->hash_fn(entry, map->cap), idx = idx0;
    
    do {
        if (map->entries[idx] == NULL || map->eq_fn(map->entries[idx], entry))
            return &map->entries[idx];
    } while ((idx = (idx + 1) % map->cap) != idx0);
    return NULL;
}

static void rehash(struct hash_map* map) {
    void** old_entries = map->entries;
    integral_t old_cap = map->cap;

    map->cap = (map->cap + 1) << 1;
    map->entries = ccc_alloc(map->cap * sizeof(void*));

    for (integral_t i = 0; i < old_cap; i++) {
        if (old_entries[i] == NULL) continue;
        void** cell = hm_cell_r(map, old_entries[i]);
        if (cell == NULL) {
            fprintf(stderr, "ccc: rehash failed, likely a bug\n");
            exit(1);
        }
        *cell = old_entries[i];
    }

    free(old_entries);
}

void** hm_cell_w(struct hash_map* map, const void* entry) {
    void** cell = hm_cell_r(map, entry);
    while (cell == NULL) {
        rehash(map);
        cell = hm_cell_r(map, entry);
    }
    return cell;
}